Lavet stepping motor with U-shaped coil core

Abstract

A stator for a stepping motor of an electric watch comprises an elongated yoke member having a free end, a coil arm integrally formed on the other end of the yoke member and having a free end, an exciter coil arranged on the coil arm by being pushed onto this coil arm from the free end thereof, and a bridge member connecting the free ends of the yoke member and the coil arm, the yoke member with the coil arm and the bridge member hereby being flat elements made of a magnetizable sheet metal. In accordance with the invention, the coil arm is of a greater length then the exciter coil and the bridge member rests flat on the free ends of the yoke member and the coil arm and areally overlaps regions of these elements.

What is claimed is: 
     
       1. A stator for a stepping motor of an electric watch comprising an elongated yoke member having a first free end, said yoke member defining a first mounting opening opposite said first free end, a coil arm of substantially uniform width integrally formed on the other end of said yoke member and having a second rounded free end, an exciter coil comprising a self-supporting air coil arranged on said coil arm by being pushed onto said coil arm from said second free end thereof, and also comprising a bridge member connecting said free ends of said yoke member and said coil arm, said yoke member with said coil arm and said bridge member hereby being flat elements made of a magnetizable sheet metal, characterized in that said coil arm is of a greater length than said exciter coil and that said bridge member defines a second mounting opening and rests flat on said free ends of yoke member and coil arm and areally overlaps regions of these elements whereby said mounting plate may be tightened against said first and second free ends with a mounting screw to ensure a magnetic path of good conductance in said regions and wherein said yoke defines a rotor opening opposite a mid portion of said exciter coil and disposed between said mounting openings.